That "guy" is God (2 Peter 1:20,21)and since you disavow this you are saying that Christians have no basis for Intelligent Design arguments. And since you won't allow Scripture in this discussion it is considered over.
No. It's some guy claiming to talk for God. You accept, uncritically, the claims the Bible makes for being the Word of God. Yet you really have nothing other than the words in the Bible to base that acceptance upon.